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Split brain.

by: National Educational Television and Radio Center

Publication date: 1964

Topics: 16mm Film, Educational Film, Cerebral hemispheres, Brain, Human anatomy, Medicine

Publisher: Bloomington, Ind. : NET

Digitizing sponsor: Internet Archive

Contributor: Internet Archive

Language: English

Demonstrates and explains experiments performed by the California Institute of Technology utilizing animals and humans in which the two cerebral hemispheres have been separated surgically. Evaluates results in terms of their contribution to our knowledge of how the brain works

Summary

Explains the revolutionary split - brain operation, performed at the California Institute of Technology, in which the two hemispheres of the brain are separated surgically along the corpus callosum. Demonstrates devices developed to test split - brain subjects to provide insight into the functioning of the brain.

Addeddate: 2015-02-20 21:56:29

Boxid: 1113023

Identifier: splitbrain

Oclc_id: 3991563

Ocr: The. Program. Is from N E T. Occasional television. Everything we human beings ever do no matter our canary it seems has a complex beginning in our brains. Finding out how the brain does this work is a study that is fascinated scientists for centuries. One puzzling aspect of the study is the fact that all our activities are controlled not by one brain but by to enter connected a half brain why do we have a double braid. Dr R.W. Sperry of the California Institute of Technology is seeking the answer. Working with him on a series of unique experiment is Dr Michael Gazzaniga. The brain of the course of the enormously complex structure in fact it's kind of redundantly complex we had two cerebral hemispheres in the body we have to Putin needs we have to double nature throughout the whole body system now we know that the the long in the kidney can operate separately and independently but it becomes a fascinating question tonight whether the two cerebral hemispheres can operate separately and independently are how dependent are the well the way to get at this question would be to separate the two cerebral hemispheres by the major interest in this very connection and we do the surgically in the canon monkey by sectioning the structure as can be seen in this affray and section it all the corpus callosum in it has over two million nerve fibers and they originally interconnect the to have the brain once this is a section I want to react to the question of what can the cerebral hemispheres do we have to be able to allow the lies the sensory input to one or the other cerebral hemispheres we have to make an additional surgical lesion and at that the point where the optic nerves come back from the i's and cross It's called the optic causing it by sectioning down the middle line the optic eyes and we can in effect make it so that what the animal sees through the left eye is primarily a projected to the left hemisphere and what the animal sees to the right I only the right hemisphere sees and by sectioning the optic I as a man in addition the corpus callosum as we've explained we can begin to test the dependent an independent each cerebral hemispheres. The approach is quite simple you make of midline incision over the top of the animal school and you turn a rather large bone flap back so that you can expose the brain over the midline. This matter is a protective covering of the brain and it has to be cut back also in order to get right into the cerebral hemispheres. Once this is. One separates the cortex the retractor goes down and between the cerebral hemispheres by using a suction technique. The instrument used for sectioning the corpus callosum is merely a converted hypodermic needle that is soaked onto a suction pump and with the lights on a section This is placed down in between the cerebral hemispheres and it is used second way they corpus callosum brain tissue so as not to injure the surrounding blood vessels now you also have to keep going down deeper in the brain to get at the optic I asked him which is the part of the brain and also has to be section in order to limit the animal studies to one eye to one particular hymns there once that is done bone flap is replaced animal sewn up and within a day's effing hopping around and has no major problem. With the operation isn't nearly as dramatic as one might think it would be there are no noticeable the Haven roleplaying their personality doesn't change in fact there are instances where a monkey was King our name was operated upon only surgery he was still king of the colony and none of the Monkeys can detect that he had been all over. This is a specially split among you. He's mediately said today in the cage made him for nominee will be playing like any of your point monkey should lead. In spite of its normal behaviour. Radical changes have taken place in the mental processes of the split brain monkey. To measure the changes. Dr Sperry and his associates developed this elaborate testing device. It tests one half of the monkey's brain without involving the other in a doctor because then I got a test one hemisphere by making the animal retrieve food with its right hand using only its sense of touch. Denny's switches access to the food to the left hand and the other half of the brain and we see that the left hand becomes as proficient as the right to tentative conclusions are possible first the two halves of the split brain can operate independently as though each were a single brain. Second there is no transfer of information between the two hemispheres. Testing these conclusions for the rebring soon to play the monkey sense of vision. It makes the animal peer through and I hold that a response plan load bearing to symbols using one eye and one of its top brains it learns to press the triangle to receive a food allergy reboard. All. The eye hole is switched and the monkeys other I in the have brain are introduced to the panel. It is now confused and make many mistakes on the left brain which knows how to do the trick cannot pass its knowledge to the right brain. The test confirms the previous conclusions in the split brain monkey the two halves of the brain have separate memories and can perform independently. Do these conclusions apply to the human brain to find two subjects were tested brands have been section to relieve epilepsy. Test results show that speech is localized in only one brain. Dr this reconstructs the test must remember though that in this surgery on these two people their optic Kyle them was not section that was in the monkey for because there was no reason to section and therefore what these people when they look through one I visually information goes to build him affairs we can't have that in our specific testing situations using this gadget. We've made we can prevent that proves that the anatomy of the human visual system allows for that when a person to fixate on a central point what one sees to the left of that point is projected to the right hemisphere and what one sees to the right of that point is projected into the left hemisphere so that brain person can be sitting here and when we flash on a picture and orange into the right visual field that information is only projected in the left hemisphere and we found that the patient says he describes it as an orange and no matter what the stimuli words pictures and they describe in a correct manner similar visual stimuli are flashed into the left visual field which go to the right hemisphere such as a fork like you see here the patient will say when asked. We will the experiment last what did you see an expert on the patient to say I didn't see anything. An experimental to think tanks barrels and say well I take out the car the best describes what you may have seen and sure enough the patient goes out very calmly and pointed to the word for so that what happens on the split brain patient is that all the sensory information that is protected and arrives in the left hemisphere can be talked about but all that information the rise in the right hemisphere perceived and acted upon but it is not talked about because the patient has no awareness of it in terms of his ability to verbal e audibly express it out loud. If speech originates in the left half of the brain are there any functions special to the other. Here a split brain subject provides the answer as it tries to copy this pattern with blocks we discover is ability is confined to his right brain. Now let's remember that the left hand is governed from the right hemisphere and you will see that he has absolutely no problem in solving the problem on the patient tries to solve the problem with this right here in which is govern from the left hemisphere we find that he is not capable of doing it. Namely that the right hand which is governed from the left hemisphere is intrinsically incapable of performing this kind of visual constructional tat it's interesting to note that the whole perspective this guy and he had three in one block combinations doesn't even square them up. You can feel left and wants to keep helping the right. We're now seeing at the left hand can perform the problem and the right hand cannot now a question of tell us what happens when you allow both A and together to try to solve the problem and what we find out is that they fight over each other one hand on one hand is not and so they more or less squabble and the reason for this is that the the hemispheres are disconnected the right hemisphere controls the left and on the left and the spear trolls right here and these are almost mutually independent system that was two people were fighting over performing this task one knew how no one didn't and one would fight for dominance of the situation. One of the game through this research into split brains it is not possible to localize and one half brain basic mental processes like learning and memory. This cuts the complexities of brain research almost enough so that in the future we can expect to achieve deeper insights into the mechanics of how the brain really works. The of. This is in the to the the National Educational Television Network.